Characterization of monoclonal antibodies to conserved antigens of Entamoeba histolytica and E. dispar and development of a stool ELISA

Differentiation of Entamoeba histolytica and Entamoeba dispar infections

In this article, Terry jackson and Jonathan Ravdin briefly review the latest information on monoclonal antibody-based ELISAs that use antigen capture as a tool in the differential detection of human infection with Entamoeba histolytica and E. dispar. Current technology of culture and isoenzyme analysis is not widely available, is cumbersome and too time-consuming. A further potential benefit of antigen detection tests is that they can be used to monitor the efficacy of therapy; this is a shortcoming of serological tests owing to the persistence of the antibody response after successful treatment.

A single-step immunochromatographic test for the detection of Entamoeba histolytica antigen in stool samples

A rapid, single step, sensitive and specific immunochromatographic test for the detection of E. histolytica antigens in the stool samples is described. Monoclonal antibody AC55 specific for E. histolytica was used as capture antibody on nitrocellulose sheet. The same antibody was conjugated to colloidal gold to detect the presence of antigen. In this test, multiple steps of washing, incubation, etc. are not required and there is no need for secondary colour development as gold particles produce a typical reddish, purple colour, when they bind to the solid phase at the site of immune reaction. 151 stool samples from patients with suspected amoebiasis were screened by this assay. Sensitivity of the test was found to be 97.6% and specificity 92.6%. 25 polyxenic E. histolytica cultures and other cultures were also tested. The test did not show positive reaction with other intestinal parasites.

Evaluation of an antigen-capture enzyme immunoassay for detection of Entamoeba histolytica in stool samples

In order to identify the prevalence of Entamoeba histolytica in tourists with diarrhoea returning from countries of the developing world, sensitivity and specificity of a commercially available enzyme immunoassay (EIA) kit for the detection of Entamoeba histolytica coproantigen in stool were evaluated. Five hundred seventy-seven specimens from 469 patients were examined by microscopy and EIA. Sixty-two specimens from 49 patients were considered positive for Entamoeba histolytica. Compared with microscopic examination of stool samples, the EIA was found to be slightly more sensitive (90.3% vs. 87.1%) and was 97.7% specific for Entamoeba histolytica.